A Combined Experimental and Theoretical Study of ESR Hyperfine Coupling Constants for -Tetrasubstituted -Phenylenediamine Radical Cations.

A test set of -tetrasubstituted -phenylenediamines are experimentally explored using ESR (electron spin resonance) spectroscopy and analysed from a computational standpoint thereafter. This computational study aims to further aid structural characterisation by comparing experimental ESR hyperfine coupling constants (hfccs) with computed values calculated using ESR-optimised "J-style" basis sets (6-31G(d,p)-J, 6-31G(d,p)-J, 6-311++G(d,p)-J, pcJ-1, pcJ-2 and cc-pVTZ-J) and hybrid-DFT functionals (B3LYP, PBE0, TPSSh, ωB97XD) as well as MP2. PBE0/6-31g(d,p)-J with a polarised continuum solvation model (PCM) correlated best with the experiment, giving an 2 value of 0.

Prediction of the standard potentials for one-electron oxidation of ,,',' tetrasubstituted -phenylenediamines by calculation.

The formal potentials for the reversible one-electron oxidation of ,,',' tetrasubstituted -phenylenediamines in acetonitrile have been applied as a test set for benchmarking computational methods for a series of compounds with only small structural differences. The aim of the study is to propose a simple method for calculating the standard oxidation potentials, and therefore, the protocol is progressively developed by adding more terms in the energy expression. In addition, the effect of including implicit solvation models (IEFPCM, CPCM, and SMD), larger basis sets, and correlation methods are investigated.

Synthesis of radiaannulene oligomers to model the elusive carbon allotrope 6,6,12-graphyne.

Graphyne allotropes of carbon are fascinating materials, and their electronic properties are predicted to rival those of the "wonder material" graphene. One allotrope of graphyne, having rectangular symmetry rather than hexagonal, stands out as particularly attractive, namely 6,6,12-graphyne. It is currently an insurmountable challenge, however, to design and execute a synthesis of this material.

The quest for determining one-electron redox potentials of azulene-1-carbonitriles by calculation.

Electrochemical processes drive many chemical and biochemical reactions. Theoretical methods to accurately predict redox potentials are therefore crucial for understanding these reactions and designing new chemical species with desired properties. We have investigated a theoretical methodology using electronic structure methods based on density functional theory and continuum solvation models.

Subphthalocyanine-radiaannulene scaffold - a multi-electron acceptor and strong chromophore.

Two subphthalocyanine (SubPc) units and a perethynylated, alkyne-expanded radiaannulene (RA) were fused together by a four-fold Sonogashira reaction to give a compound exhibiting: (i) four reversible one-electron reductions, the first signalling good acceptor strength of the RA core itself, while the following three are a consequence of the entire scaffold, and (ii) intense light absorption that spans a remarkably broad region.

Tetraceno[2,1,12,11-opqra]tetracene-extended tetrathiafulvalene - redox-controlled generation of a large PAH core.

Two tetraceno[2,1,12,11-opqra]tetracene-extended tetrathia-fulvalenes were prepared and found to undergo reversible conversion into their planar polycyclic aromatic hydrocarbons (PAHs) upon electrochemical oxidation - at potentials probing the best valence bond representations.

Synthesis and Single-Molecule Conductances of Neutral and Cationic Indenofluorene-Extended Tetrathiafulvalenes: Kondo Effect Molecules.

Development of molecules that can switch between redox states with paired and unpaired electrons is important for molecular electronics and spintronics. In this work, a selection of redox-active indenofluorene-extended tetrathiafulvalenes (IF-TTFs) with thioacetate end groups was prepared from a readily obtainable dibromo-functionalized IF-TTF building block using palladium-catalyzed cross-coupling reactions, such as the Suzuki reaction. The end groups served as electrode anchoring groups for single-molecule conductance studies, and the molecules were subjected to mechanically controlled break-junction measurements with gold contacts and to low-bias charge transport measurements in gated three-terminal electromigration junctions.

Multistate Switches: Ruthenium Alkynyl-Dihydroazulene/Vinylheptafulvene Conjugates.

Multimode molecular switches incorporating distinct and independently addressable functional components have potential applications as advanced switches and logic gates for molecular electronics and memory storage devices. Herein, we describe the synthesis and characterization of four switches based on the dihydroazulene/vinylheptafulvene (DHA/VHF) photo/thermoswitch pair functionalized with the ruthenium-based Cp*(dppe)Ru ([Ru*]) metal complex (dppe=1,2-bis(diphenylphosphino)ethane; Cp*=pentamethylcyclopentadienyl). The [Ru*]-DHA conjugates can potentially exist in six different states accessible by alternation between DHA/VHF, Ru(II) /Ru(III) , and alkynyl/vinylidene, which can be individually stimulated by using light/heat, oxidation/reduction, and acid/base.

Similar strength of the NH···O and NH···S hydrogen bonds in binary complexes.

The weakly interacting complexes of dimethylamine with dimethyl ether (DMA-DME) and with dimethylsulfide (DMA-DMS) have been detected in the gas phase using Fourier transform infrared spectroscopy at room temperature. The observed redshift of the fundamental NH-stretching frequency was found to be extremely small with only 5 and 19 cm(-1) for DMA-DME and DMA-DMS, respectively. The experimentally determined integrated absorbance has been combined with a calculated oscillator strength to determine an equilibrium constant of 2 × 10(-3) and 4 × 10(-3) for the DMA-DME and DMA-DMS complexes, respectively.